The behavior of the neural membrane can be described exceedingly well with the Hodgkins-Huxley equations, which can be simulated with dynamical systems tools.

To simplify the dynamics of the membrane, the Hodgkins-Huxley equations can be simplified to a 2-parameter system, described by the Fitzhugh-Nagumo model.

Idealized effects of feedback on the membrane potiential, and simple neural networks, can be simulated with simple feedback systems.

Neuromorphic systems, which implement neural circuits with analogVLSI, allow the systematic investigation of realistic larger neural networks, and the application of such systems for ultra-low energy and/or very fast responding applications.

The chapter on simulations of the retinal function provides a software simulation of human retina based on a biological inspired model. It shows how retina, receives, transmits and processes visual information for higher visual cortical structures.

The chapter on simulations of the somatosensory system describes how muscle spindles can be simulated. Complete simulations of the somatosensory system are difficult, since this system includes not only the limb dynamics (which are complex on their own), but also additional complexities caused by the redundancy of muscles for limb movements.

The chapter on efficient coding describes how natural images and natural sounds are encoded by the brain and how the efficient coding model replicates this process. It was found that the process of both input signals could be modeled with very similar methods. The goal of efficient coding theory is to conceil a maximal amount of information about a stimulus by using a set of statistically independent characteristics.

Our understanding of the neural processes underlying hearing, seeing, and orientation sensing are remarkably advanced. On the gadget side, we have corresponding vision, sound, and movement sensors available for robotics applications. The processes of smell and taste, however, seem to be remarkably more complex. This complexity is hinted at by the sheer number of physiological sensors available to our respective senses: we have one to two types of transducing cells for hearing and for movement sensing (regular and irregular hair-cells), and about four types of light transducing cells in the retina (the three types of cones for color vision, and the rods for light/dark sensation). Instead, we have hundreds of taste- and smell- receptors in our nose and on our tongue. It makes sense, therefore, that despite being functional, current artificial noses and tongues are not yet very advanced. The chapter on simulations of the olfactory system describes our first attempts at computationally describing the olfactory system and its properties - that is to say, how we come to smell.